In pipelines it is frequently necessary to position one or more pipes carrying a line medium within a rigid outer casing. This carrier pipe within an outer casing arrangement is frequently provided for water and sewer mains within highway and railroad crossing pipe casings to maintain carrier pipe alignment, restrain the carrier pipe against floatation or other movement, or maintain the carrier pipe in a fixed position and orientation such as per grade requirements in the case of a gravity sewer.
One prior approach to positioning a carrier pipe within an outer casing involves banding wooden skids to the outer periphery of the carrier pipe with steel straps. This approach requires at least two workers to attach the wooden skids to the carrier pipe, is cumbersome and time consuming, and frequently results in the catching of the wooden skids on weld beads resulting in rotation of the carrier pipe and destabilizing of its joints. Moreover, the wooden skids and steel straps are subject to breaking, making removal and reinstallation necessary. Back filling using sand or gravel is also employed to stabilize the carrier pipe, making subsequent removal such as for repair or rehabilitation even more difficult and expensive. A wet back fill produces a galvanic cell effect which promotes corrosion.
The banded wooden skids have generally been replaced by stainless steel casing spacers. These prior art casing spacers typically include upper and lower semi-circular shell members which are typically coupled together along their adjacent edges by means of a plurality of nut and bolt combinations inserted through flanges on the edges of the shell members. Disposed about the outer peripheries of the shell members are a plurality of spaced risers which maintain the carrier pipe in a fixed orientation and spaced position from the outer casing as well as from other pipes within the casing. While more easily installed and removed than the banded wooden skids described above, prior art steel casing spacers have also been cumbersome to install requiring two workers and a considerable amount of time.
The present invention addresses the aforementioned problems encountered in the prior art by providing a casing spacer which can be easily and quickly installed by a single worker which includes a unique coupling between the pair of shell members disposed about the carrier pipe.